Morphologie etc. — Varietäten, Descendenz, Hybriden. 533 



in all essential features with Vitis and Laminaria, the connecting 

 threads in the young transverse wall of the sieve tube are each 

 bored out to form a Single slime string enclosed in a tube of callus. 



The development of the haustorium of Ciiscuta is described, 

 shewing that the tissue owes its origin to the fusion of separate 

 Strands of cells, so that all the cells composing it are not geneti- 

 cally connected with one another. 



The hyphae composing the haustorium each subdivide to form 

 the Strands of cells and connecting threads are confined to he newly 

 formed cell-walls, i. e. genetically connected cell-walls, they never 

 occur on walls associated with each other by later growth. 



The behaviour of the wall at the tip of an invading hypha is 

 fully described, and the author gives evidence to shew that junction 

 with the sieve areas of the host is effected by the application of the 

 naked protoplasm of the hyphal tip to a functional sieve plate or 

 field of the host — the parasite wall being dissolved away in the 

 region over the sieve area. The functional efficiency of this arran- 

 gement is discussed and it is concluded that the passage of food 

 substance from host to parasite is of the nature of passive filtration, 

 the internal pressure forcing the contents of the host sieve tubes 

 through the lateral sieve fields into the parasite. Evidence is given 

 in the paper to shew: 



1. The functional efficiency of sieve tubes in general, and of 

 sieve fields and sieve plates in particular. 



2. The formation of callus by direct deposition and by changes 

 in already formed walls. 



3. The connecting threads occur only between genetically con- 

 nected cells, their origin being associated with the processes of 

 cell division. E. de Fraine. 



Wager, H. and A. Peniston. Cytological Observations of 

 the Yeast Plant. (Ann. Bot. XXIV. p. 45—83. 1910.) 



Describes in detail the structure of the yeast cell with its nucleus. 

 The nucleus has no well marked nuclear membrane, it consists of 

 a nucleolus and a chromatin net work which forms a peripheral 

 layer round a nuclear vacuole. 



The nucleus and its vacuole divide amitotically at bud formation. 

 During spore formation the vacuole and network disappear and the 

 nucleolus, after it has become surrounded by chromatin granules, 

 divides by constriction. E. G. Welsford. 



Regel, R„ Anzahl der Sepalen bei Anemone uemorosa L. 

 (Bull. Bureau angew. Bot. p. 256—264. St. Petersburg 1911.) 



An 3 Standorte in N.O. -Russland studierte Verf. das Variie- 

 ren der Anzahl der Sepalen von Anemona nemorosa. Die bei Pe- 

 tersburg gefundene Rasse ist die gleiche wie in Galizien (von 

 Chmielewski studiert) und in England (von G. Udney Jule 

 beobachtet), welche unter günstigen Entwicklungsverhältnissen eine 

 grössere Zahl von Sepalen (7 und mehr) bildet. An den beiden 

 anderen Orten (Ssestra-Fluss an der finnischen Grenze und beim 

 Flusse Ochta) zeigte sich ein entschiedenes Vorwiegen der Sechs- 

 zahl mit geringer Variabilität. Matouschek (Wien). 



Schulz, A., Die Geschichte des Roggens. (39. Jahresber. 



